He sent us a start of his to get us started. Here it is, all bubbly and awesome. We're playing with now, figuring out how it works - this is NOT the synthetic fast rise yeast that you buy at the store.
We'll keep you posted.
Here's a link to The Art of Baking with Natural Yeast by Caleb Warnock and Melissa Richardson. You can pre-order it now. It's due out August 14th.